#include<iostream>
using namespace std;

void swap(int * p1, int * p2) {
  const int temp = *p1;
  *p1 = *p2;
  *p2 = temp;
}

int main() {
  int a = 10;
  int b = 20;
  swap(&a, &b);
  cout << a <<','<< b << endl;
  return 0;
}